If you need further assistance with the USNCO Registration Platform, please contact registrationusnco@acs.org
Parents and guardians seeking to register students for participation in the 2026 U.S. National Chemistry Olympiad (USNCO) must contact their USNCO Coordinator.
110 min | 60 multiple-choice questions
Covers broad chemistry topics
90 min | 60 multiple-choice questions
Covers broad chemistry topics
105 min | 8 written questions
Covers chemical theories and models
90 min | 2 laboratory practicals
Involves problem solving in the laboratory
Multiple choice USNCO (both local and national) exams cover the following topics:
| Questions | Topic |
|---|---|
| 1 – 6 | Stoichiometry/Solutions |
| 7 – 12 | Descriptive/Laboratory |
| 13 – 18 | States of Matter |
| 19 – 24 | Thermodynamics |
| 25 – 30 | Kinetics |
| 31 – 36 | Equilibrium |
| 37 – 42 | Oxidation - Reduction |
| 43 – 48 | Atomic Structure/Periodicity |
| 49 – 54 | Bonding/Molecular Structure |
| 55 – 60 | Organic/Biochemistry |
More than 1,000 students sit for the three-part National Exam each April. Coordinators nominate students for the National Exam based on the results of the Local Competitions. Each Local Section can nominate only a certain number of students determined by the number of its ACS members. No more than two students from any given school can compete in the National Exam.
See the allowed number of nominees below, or download a PDF of the allotment of nominees by ACS Local Section.
| ACS Members | USNCO Nominees |
|---|---|
| 1–1000 | 12 |
| 1001-1350 | 13 |
| 1351-1700 | 14 |
| 1701-2050 | 16 |
| 2051-2400 | 17 |
| 2401-2750 | 18 |
| 2751-3100 | 19 |
| 3101-3450 | 20 |
| 3451-3800 | 22 |
| 3801-4150 | 23 |
| ACS Members | USNCO Nominees |
|---|---|
| 4151-4500 | 24 |
| 4501-4850 | 25 |
| 4851-5200 | 26 |
| 5201-5550 | 28 |
| 5551-5900 | 29 |
| 5901-6250 | 30 |
| 6251-6600 | 31 |
| 6601-6950 | 32 |
| 6951-7300 | 34 |
| 7301-7650 | 35 |
ACS calculates the average number of correctly answered questions by topic area. Based on this average, each student's score in a particular topic is compared to the overall average and rated as: Below Average, Average, Above Average, or Outstanding Performance.
Only student scores for Part I (multiple-choice) are sent to the Local Section coordinators to be distributed to students.
The 20 top-scoring students are invited to attend a study camp to compete for a spot in the U.S. team. Based on the score of their overall performance, some students are recognized with High Honors and Honors and receive a certificate from the USNCO national office. Approximately the top 50 students are recognized as High Honors and the next 100 as Honors. The list of High Honor and Honor students is published on the USNCO website. The top student (and teacher) in each local section exam
Learn about the exam format and how to prepare for exams.
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